The surveillance programme for Aphanomyces astaci in Norway 2017
Research report
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https://hdl.handle.net/11250/2656179Utgivelsesdato
2018Metadata
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Sammendrag
In this surveillance program, we used environmental DNA (eDNA) monitoring of the water as an alternative method to the traditional cage experiments with live noble crayfish. Here, DNA from spores of Aphanomyces astaci are detected directly from water filtrates. We also determine the presence/absence of eDNA from noble crayfish (Astacus astacus) and signal crayfish (Pacifastacus leniusculus) to supplement the results and to gain the possibility to evaluate the habitat status in more detail. The main geographic focus of this surveillance program has been on the Halden watercourse and neighbouring risk areas. Other covered geographic areas include the Mosse watercourse, Glomma watercourse, and selected areas in Eidskog including the Buåa watercourse, the Vrangselva watercourse and River Finnsrudelva. In total, 57, 32, 16 and 32 water samples were collected from selected sites in the Halden-, Mosse-, Glomma watercourse regions and in the Eidskog region, respectively. Locations for sampling water were strategically selected and focused on both control zones and in the risk areas adjacent to crayfish plague control zones. The presence/absence of the three target species was determined simultaneously through screening with species-specific qPCR assays. In 2017, no spread of A. astaci was observed in any of the monitored areas. - In the control zone of the Halden watercourse, A. astaci eDNA was only detected in the southern part of Lake Rødenessjøen. Here, the known presence of signal crayfish was confirmed by eDNA detection. No sign of crayfish plague was observed from the northern part of Lake Rødenessjøen (Kroksund) up to the control zone border at Fosserdam. This result was supported by positive detections of noble crayfish eDNA in all water samples from River Hølandselva and upstream. All water samples in this risk area were negative for A. astaci and signal crayfish, while positive for noble crayfish eDNA. - In the Mosse watercourse, no eDNA of A. astaci and signal crayfish was detected, while noble crayfish eDNA was detected in Lake Våg. - In the Glomma watercourse, no sign of crayfish plague was found, and the samples were negative for all screened targets. - In Eidskog municipality, no samples were positive for signal crayfish or A. astaci, while several were positive for noble crayfish eDNA in the Vrangselva watercourse and River Finnsrudelva.